1. Field of the Invention
The present invention relates generally to an apparatus and method for searching for 3-dimensional shapes and, more particularly, to an apparatus and method for searching for 3-dimensional shapes, which convert a 3-dimensional shape, such as the shape of a metallic mould product, into 2-dimensional image data and quickly and accurately search for an identical or similar 3-dimensional shape using the 2-dimensional image data.
2. Description of the Related Art
Recently, with the development of computer and communication technology, demand for multimedia information service is increasing. The necessity for research into 3-dimensional shape searching technology, which can be used to search still images and moving images through the Internet, Video On Demand (VOD) service to be used for broadcast production, an electronic library, a medical field (tele-medicine and medical image search) and the like, is increasing. In the early stages of research, a method of a user's directly adding indices to all the 3-dimensional shapes of an object targeted for searching, for example, a kettle having one of various shapes and a metallic press mould for an automobile, was used. For example, information about the bottom diameter of a kettle, the diameter of the lid of the kettle, and the height of the kettle (information about a shape) is indexed in text form, and 3-dimensional image data is prepared using the indexed information and are stored in a storage means, such as a computer.
Thereafter, in order to search for an object whose information previously stored, the user directly inputs the article name of the object and information about the shape thereof through the input means of the computer, so that the object corresponding to the input information can be searched for. The method of searching using the information in text form can be effective when the number of objects to be stored is small and the amount of information about the shapes of the objects is small. However, when the types and number of objects increase, or information about the shapes of respective objects is complicated, a lot of time is required to search for an identical or similar object and search accuracy is lowered. Furthermore, since the target of the search is not an actual object but information in text form, there is a problem in that information about a shape represented for a specific object can be different for different users. Furthermore, the problem is further serious when the shape of an object cannot actually be represented in text from. Furthermore, since the user must directly input respective information about the shapes of all the objects, efficiency is lowered from the point of view of consumed time and cost.
Meanwhile, there is another method of performing search in such a manner that the 2-dimensional images of objects that are produced at a specific time, like pictures, are previously stored in a computer, and an identical or similar 2-dimensional image stored in the computer is searched for using the 2-dimensional image of an object in question. This method is an objective and effective method, in contrast to the above-described method of comparing a 3-dimensional shape with text information.
However, when 2-dimensional images being used, for example, the face shape of a human and the shape of an automobile, vary with the user's viewing angle, the method cannot be used as a search method because consistency cannot be maintained. Furthermore, the method cannot be used at all in the case where a vacant space, which cannot be viewed from the outside, exists inside an object.